1. Field of the Invention
The present invention relates to a cassette processing apparatus for use with at least one of a cassette loader for loading a cassette housing a recording medium capable of storing radiation image information and a cassette unloader for unloading such a cassette.
2. Description of the Related Art
Heretofore, there have been known a radiation image information reading apparatus employing a stimulable phosphor panel that stores part of radiation energy applied thereto and emits the stored radiation energy in response to stimulating light such as visible light applied thereto.
Usually, after the radiation image information of a subject is stored in a stimulable phosphor panel that is housed in a cassette, the cassette is loaded into a radiation image information reading apparatus. In the radiation image information reading apparatus, the stimulable phosphor panel is taken out of the cassette, and the radiation image information stored in the stimulable phosphor panel is read. If necessary, remaining radiation image information is erased from the stimulable phosphor panel. Thereafter, the stimulable phosphor panel is brought back into the cassette and unloaded from the radiation image information reading apparatus for storing the radiation image information of another subject.
It has been desired to successively process a number of cassettes for efficiently reading stored radiation image information from stimulable phosphor panels housed in the cassettes. For successively processing a number of cassettes, there has been known an automatic storage phosphor cassette loader as disclosed in Japanese Laid-Open Patent Publication No. 7-25418, for example.
As shown in FIG. 8 of the accompanying drawings, the disclosed automatic storage phosphor cassette loader, generally designated by 1, has a main housing 2 including a portal 4 that can be opened and closed by a door 3. When the portal 4 is opened by the door 3, it provides access into the main housing 2. The portal 4 has a pair of vertical conveyors 5a, 5b horizontally spaced a constant interval from each other. The conveyors 5a, 5b comprise respective endless belts 6a, 6b having respective arrays of spaced ledges 7a, 7b. 
The main housing 2 has a loading cassette site 8a, a reading cassette site 8b, and an unloading cassette site 8c which are arranged in a vertical array on the conveyors 5a, 5b. 
The automatic storage phosphor cassette loader 1 operates as follows: The operator opens the door 3, places a storage phosphor cassette 9 in the loading cassette site 8a, and then closes the door 3. Then, when the conveyors 5a, 5b are actuated, the storage phosphor cassette 9 is fed downwardly into the reading cassette site 8b. In the reading cassette site 8b, a reader, not shown, removes the storage phosphor from the storage phosphor cassette 9, and reads stored radiation image information from the storage phosphor.
Thereafter, the storage phosphor is returned into the storage phosphor cassette 9, which is then fed into the unloading cassette site 8c by the conveyors 5a, 5b. After the conveyors 5a, 5b are stopped, the storage phosphor cassette 9 is taken out of the unloading cassette site 8c. 
In the conventional automatic storage phosphor cassette loader 1, adjacent ones of the ledges 7a, 7b for placing the storage phosphor cassette 9 thereon are spaced a constant interval from each other. If a storage phosphor cassette 9 of smaller dimensions, for example, is to be placed on the conveyors 5a, 5b, then adapters or pallets designed to handle such a smaller cassette have to be used on the conveyors 5a, 5b. Consequently, when a wide variety of storage phosphor cassettes 9 of different dimensions are to be used in the conventional automatic storage phosphor cassette loader 1, it is considerably troublesome to handle those storage phosphor cassettes 9.